Comment 0 for bug 1690316

The method looks like:

    def _fail_workflow(self, final_context, msg):
        if states.is_paused_or_completed(self.wf_ex.state):
            return

        output_on_error = {}
        try:
            output_on_error = data_flow.evaluate_workflow_output(
                self.wf_ex,
                self.wf_spec.get_output_on_error(),
                final_context
            )
        except exc.MistralException as e:
            msg = (
                "Failed to evaluate expression in output-on-error! "
                "(output-on-error: '%s', exception: '%s' Cause: '%s'"
                % (self.wf_spec.get_output_on_error(), e, msg)
            )
            LOG.error(msg)

        self.set_state(states.ERROR, state_info=msg)

        # When we set an ERROR state we should safely set output value getting
        # w/o exceptions due to field size limitations.
        msg = utils.cut_by_kb(
            msg,
            cfg.CONF.engine.execution_field_size_limit_kb
        )

        self.wf_ex.output = merge_dicts({'result': msg}, output_on_error)

        if self.wf_ex.task_execution_id:
            self._schedule_send_result_to_parent_workflow()

So, we first utils.cut_by_kb() for "msg" but then, essentially, add 'output_on_error' to it so the resulting size of 'output' may be greater than cfg.CONF.engine.execution_field_size_limit_kb